According to the clinical behaviors and development patterns, Acute Renal Failure can be classified into three stages: oliguric stage, diuresis stage, and recovery stage.
Oliguric (or anuria) Stage:
The main clinical behaviors of patients in this stage are nausea, vomiting, dizziness, weakness, restlessness, drowsiness and even coma. The patients may present with hypertension, pulmonary edema, heart failure, etc. In addition, if the patients were accompanied with infections, wound and fever, uremic syndrome would appear. Characters of This Stage:
◆ Decrease of Urine: urine less than 400ml is Oliguric, and less than 100ml anuria. Patients with ARF seldom have anuria, however, once occurring, it usually has a poor prognosis.
◆Progressive Azotemia: Due to the decrease of urine, the excretion of azotemia and other waste products will accordingly reduce. As a result, it leads to the increase of serum creatinine and blood urea nitrogen.
◆ Water and Electrolyte Disorders, and Acid-Base Imbalance:
(1) Excess Water: The decrease of urine excretion will lead to the retention of water in the body, causing edema, hypertension, acute heart failure and cerebral edema.
(2) Hyperkalemia: Normally, 90% of potassium is excreted by urine. In the stage of Oliguric, due to the retention of considerable potassium, the patients may be attacked by severe hyperkalemia in several hours.
(3) Metabolic Acidosis: For the normal person, the Acid metabolites is 50~100mmol each day, 80% of which is excreted in urine. Therefore, in oliguric stage, the patients will have metabolic acidosis.
(4) Hyponatremia and Hypochloremia: They usually come together. Sever hyponatremia will cause acute cerebral edema, while hypochloremia will induce vomiting, diarrhea, hyperspasmia and other metabolic alkalosis symptoms.
(5) Hypermagnesemia: In oliguric stage, the patients can not effectively excrete the magnesium, 40% of which is excreted in urine in normal times. Consequently, it may cause severe results such as breathing difficulty, myocardial depression.
(6)Cardiovascular System Symptoms：The symptoms include hypertension, arythmia, pericarditis, acute pulmonary edema and heart failure which accounts for most patients’ death in this stage.
(7) Digestive System Manifestation: The main symptoms are poor appetite, nausea, vomiting, diarrhea, and so on. Without timely treatment, it will induce upper gastrointestinal bleeding.
